Graphitization as efficient inhibitor of the carbon steel corrosion by molten binary nitrate salt for thermal energy storage at concentrated solar power

Hot corrosion by molten salts has detrimental effect on various industrial and infrastructural systems particularly on the Concentrated Solar Power (CSP) plants. To enhance durability of the CSP plants' components, while decreasing the production cost of electricity, the graphitization anticorrosion method for carbon steel in contact with molten binary nitrate salt is proposed in this work. To shed some light on the corrosion mechanisms and quantify corrosion rates a combination of advanced material characterization techniques like Focused Ion Beam, SEM, EDX, XPS depth profiling, XRD was applied. It has been demonstrated that the surface spray-coating by graphite reduces the corrosion rate at least by factor of 6 and stabilizes the corrosion scale by iron carbide crystals at 390 degrees C.